 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.forms.widgets;
 import org.eclipse.swt.dnd.DragSource;
 import org.eclipse.swt.dnd.DropTarget;
 import org.eclipse.swt.widgets.Caret;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.ScrollBar;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Widget;

 /**
  * Utility class to simplify access to some SWT resources.
  */
 public class SWTUtil {

     /**
      * Returns the standard display to be used. The method first checks, if
      * the thread calling this method has an associated disaply. If so, this
      * display is returned. Otherwise the method returns the default display.
      */
     public static Display getStandardDisplay() {
         Display display;
         display = Display.getCurrent();
         if (display == null)
             display = Display.getDefault();
         return display;
     }

     /**
      * Returns the shell for the given widget. If the widget doesn't represent
      * a SWT object that manage a shell, <code>null</code> is returned.
      *
      * @return the shell for the given widget
      */
     public static Shell getShell(Widget widget) {
         if (widget instanceof Control)
             return ((Control) widget).getShell();
         if (widget instanceof Caret)
             return ((Caret) widget).getParent().getShell();
         if (widget instanceof DragSource)
             return ((DragSource) widget).getControl().getShell();
         if (widget instanceof DropTarget)
             return ((DropTarget) widget).getControl().getShell();
         if (widget instanceof Menu)
             return ((Menu) widget).getParent().getShell();
         if (widget instanceof ScrollBar)
             return ((ScrollBar) widget).getParent().getShell();

         return null;
     }
 }

